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For Want Of A Soyuz
sckienle writes "MSNBC has an article starting "Missions to the international space station may have to be suspended because Russia cannot afford to build new craft to carry crews there...." This is a problem because a Soyuz capsule must be attached to the ISS for emergency evacuation. The problem is further complicated because any one Soyuz capsule can only be docked to the ISS for 6 months maximum. Nor are they and their boosters built for reuse. The CNN version of the information is here. I guess we need to find more billionaires to take the space vacation. How about it Mr. Gates?"
I'm afraid that paragraphs like this are enough to make most people who are familiar with even exotic launch technologies spray coffee out their noses.
Let me outline the reasons why all known methods are expensive and will remain so for the medium-term future:
Chemical rocket exhaust velocity is much lower than the delta-V required to reach orbit. This means your craft is mostly fuel. Which means that your craft needs to be strengthened to be able to carry the fuel, which means it's heavier and needs more fuel, and so forth. The end result is a large, very expensive spacecraft. Operating costs are prohibitive (never mind fuel costs - even for a mundane, commodity vehicle like a car, other costs tend to dominate).
These shouldn't be on the list at all; I'm mentioning them so that nobody tries to bring them up. These all have thrusts far too low to be used for surface-to-orbit work.
Because your exhaust temperature for a nuclear/thermal drive is limited by the temperature the materials in your reactor core can take, your Isp doesn't end up being much better than a chemical rocket, so your spacecraft is still big and very expensive.
You're also having half the environmentalists on the planet scream at you (because your exhaust is radioactive and there's a small but significant chance of you smearing your ship and reactor core over a large chunk of landscape).
On the surface, many of these exotic solutions look very nice. However, there are two problems.
Firstly, most of them require extremely high accelerations (laser launchers and railguns). Otherwise the device size becomes impractically large. Railguns or other magnetic or even compressed-gas accelerators may not _ever_ be practical to build, as even an accelerator with a thousand gravities of acceleration would have to be about half a mile long. It would need to be a vertical tower (or shaft) - firing sideways would vapourize your projectile and shed most of the velocity due to atmospheric drag, and making a track that turns up at the end would require a radius of curvature larger than the gun itself (which means you might as well build it upright to begin with).
If you're dealing with cargo that can take that kind of acceleration, or if you build a multi-station laser launcher that drives cargo mostly tangentially, or if you spend the money for a space elevator, you still have the problem of a facility that costs hundreds of billions to trillions of dollars to build, and tens to hundreds of billions of dollars per year for upkeep. In order to justify this kind of expense, and to amortize costs to even be competitive with today's launch prices, you're going to need vast amounts of cargo ready to be lifted into space. There's no convincing evidence that such a market exists (nobody's come up with a really lucractive reason to lift millions of tonnes into space, as opposed to just a few satellites). Even with a high launch volume, the maintenance costs of the facilities will keep the launch costs significant (i.e. far more than just the theoretical energy costs of sending something into space - see my fuel costs comment above).
In summary, even if you assume that alternate launch mechanisms can be built *now*, there are strong economic reasons for space travel staying expensive.